In general, a fiber-reinforced composite utilizing a thermoplastic polypropylene resin can be formed by impregnating a modified propylene to which a thermoplastic resin comprising a propylene-ethylene copolymer and a polar functional group are grafted and a polyolefin polyol containing a hydroxyl group into a continuous fiber such as glass/carbon. Such composite is excellent in impact resistance as well as in strength and rigidity.
In this case, the impregnation of the thermoplastic resin into the continuous fiber is a factor that gives a significant effect on improving the mechanical properties and impact properties of the long-fiber composite. If the impregnation of the two materials is low, the continuous fibers are not bonded in the thermoplastic resin, and cracks and pores may be formed in the composite, which can in turn adversely affect the physical properties of the composite.
Thus, although a compatibilizer has been used to improve the impregnation of the thermoplastic resin into the continuous fiber, such treatment with the compatibilizer is no longer activated in more than a certain amount. Further, an excessive treatment may adversely affect the physical properties, and has only limited control over the strength, rigidity and impact performance. Therefore, the need for a study of the factors that can enhance the impact performance in addition to the use of the compatibilizer has emerged.